US2248397A - Railway traffic controlling apparatus - Google Patents

Description

I VENTQR flowardAflz r012 H. A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS Filed March 12-, 1940 NW WW:

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July 8, 1941.

Patented July 8, 1941 UNHT 8 STATES PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS Application March 12, 1940, Serial No. 323,595

7 Claims.

My invention relates to railway traflic controlling apparatus and particularly to means for controlling operation of highway crossing signals and adapted for use in connection with railway signaling systems employing coded or periodically interrupted current in the track circuits thereof.

It is an object of this invention to provide means of the type described and in which steady energy is supplied to the track circuits to discontinue operation of highway crossing signals without conditioning the signals governing movement of trains in the track stretch to display 2. proceed indication.

A further object of the invention is to provide a system of the type described and employing a minimum of apparatus.

Another object of the invention is to provide apparatus of the type described and arranged in such manner that track relays in addition to those employed in the control of the signals governing movement of trains through the track stretch are not required.

Another object of my invention is to provide apparatus of the type described and adapted for use where more than one highway crossing is present within one track section, the equipment being arranged. so that the proper operation of the signals at the highway intersections and of the signals governing movement of trains in the track stretch will take place regardless of the direction of movement of a train through the track stretch.

A further object of the invention is to provide an improved signaling system.

I shall describe one form of system embodying my invention together with a modification thereof and shall then point out the novel features in claims.

In the drawing Fig. 1 is a diagram of a stretch of railway track equipped with apparatus embodying my invention, and.

Fig. 2 is a fragmentary view showing a modified form of apparatus embodying my invention.

Referring to Fig. 1 of the drawing there is shown therein a stretch of railway track having a pair of track rails I and 2 over which traffic normally moves in the direction indicated by the arrow, that is, from left to right. The track stretch is divided into successive track sections for signaling purposes. One complete section, identified as section HT, and parts of two other sections, identified as sections IGT and IZT, are shown. The section HT includes intersections with two highways and at each of these intersections a crossing signal is provided to warn users of the highway of the approach of a train. The crossing signals are designated XSI and XSZ, while for the purpose of controlling the crossing signals the track section HT is subdivided into four subsections which are designated Al IT, BUT, Ci IT and DHT.

Each of the principal track sections has at the entrance end thereof a wayside signal S which is capable of displaying a stop, a caution and a clear indication. Each section also has at the entrance end thereof a code following track relay TR which controls the signal for the associated track section, and also controls the supply of energy to the rails of the adjacent track section in the rear. Each of the subsections of section HT is also provided with a code following track relay. As shown the track relays are of the alternating current type, each having a winding having its terminals connected to the track rails of the associated track section.

Each of the track sections has at the exit end thereof a track transformer TT. Each of these transformers has a secondary winding one terminal of which is connected to one track rail and the other terminal of which is connected to the other track rail of the associated track section through a current limiting reactor 6.

The primary windings of the track transformers are supplied with alternating current from a suitable source the terminals of which are designated BX and OK. The circuits of the primary windings of the track transformers are controlled by the track relays of the adjacent sections or subsections in advance.

The details of the control of the wayside signals and of the circuits of the track transformer primary windings are not a part of this invention, except as hereinafter explained in detail. Any appropriate form of coded signaling apparatus may be employed, and one form of system which may be used is shown in the application of F. H. Nicholson and L. R. Allison, Serial No. 210,744, filed May 28, 1938, for Railway traffic controlling apparatus.

Since the construction and operation of the signaling system is old and well-known, the details of the signaling system have not been shown in order to simplify the disclosure.

The highway crossing signals X8! and X52 are controlled byinterlocking relays XRI and XRZ, respectively. The interlocking relays are of the type well-known in the art, and since the construction and operation of these relays, and of the circuits by which the relays control the crossing signals are well-known, the details of the relays and of the control circuits have not been shown in order to simplify the disclosure.

The track relays l 2TR and Al ITR have associated therewith suitable decoding apparatus, not shown, while the track relays BI [TR and DI ITR. have associated therewith auxiliary relays FSA which have a slow releasing characteristic such that the relay contacts when picked up remain picked up during the intervals between the picked-up periods of the contacts of the associated track relay.

The track relay CI ITR has associated therewith slow releasing auxiliary relays CI IBSA, CI IFSA and CI IFSC, which cooperate as hereinafter explained to control the circuits of windings of the interlocking relays KB! and XR2.

Each of the track relays has'associated therewith a local source of direct current the terminals of which are designated B and C in the drawing.

When the track stretch is vacant, energy of the 180 code frequency is supplied to the track relay IZTR and the equipment, not shown, associated with this relay operates to condition the signal I2S to display its clear indication, while energy of the 180 code frequency is supplied to the primary winding of the track transformer DI ITT, and by this transformer to the rails of section DI IT. This energy feeds to the winding of the track relay DIITR and produces code following operation of the track relay contacts. During the released periods of the contacts of the track relay DIITR, contact establishes the circuit of the primary winding of track transformer CI ITT, while this circuit is interrupted during the picked-up periods of the track relay contacts. Accordingly energy of the same code frequency is supplied to the rails of section CI IT as is supplied to the track relay DI ITR. However, the impulses of energy supplied to the rails of section CI IT occur during the off intervals in the code supplied to the rails of section DlIT. This back-contact coding at the cut section aids in preventing code distortion.

During the picked-up periods of the contacts of the track relay DI I'I'R contact 2| establishes a circuit to supply energy from the local source of direct current to the winding of the relay DI IFSA. This circuit is interrupted during the released periods of the track relay contacts, but the contacts of the relay DI IFSA are slow enough in releasing to remain picked up during the intervals between the supply of impulses of energy to the relay winding. Accordingly as long as the contacts of the relay DI ITR are respending to coded energy, the contact 23 of relay DI IFSA is picked up and establishes the circuit of the Winding 24 of interlocking relay XRZ, while when the track relay DIITR is not responding to coded energy contact 2| interrupts the circuit of the winding of the relay DI IFSA and contact 23 of relay DIIFSA becomes released to interrupt the circuit of the winding 24 of relay XRZ.

The ener y of 130 code frequency supplied by the track transformer CI lTT to the rails of section CI IT feeds to the winding of the track relay CI ITR and effects code following operation of the contacts of this relay. During the pickedup periods of the track relay contacts, contact 25 establishes the circuit of the primary winding of the track transformer BI ITT. This circuit is interrupted during the released periods of the track relay contacts so that impulses of energy of the same code frequency are supplied to the rails of section BI IT as are supplied to the track relay CI ITR.

During the released periods of the contacts of the track relay CI ITR contact 2'! establishes the circuit of the winding of relay CI IBSA. During the picked-up periods of the track relay contacts, contact 21 establishes the circuit of the winding of relay CI EFSB if contact 28 of relay CI IBSA is picked up, while if contact 28 of relay CI IBSA is released, contact 21 when picked up establishes the circuit of the winding of relay CI IFSC.

The circuit of the winding of the relay CI IBSA is interrupted during the picked-up periods of the track relay contacts, while the circuit of the winding of the relay CI IFSB is interrupted during the released periods of the track relay contacts. The contacts of the relays CI !BSA and CI IFSB are slow enough in releasing, however, to remain picked up during the intervals between the supply of impulses of energy to their windings when the track relay CI ITR is responding to coded energy.

The relay CIIFSB has a contact 30, which when picked up establishes circuits to supply energy to the winding 3| of interlocking relay XRE and to th winding 32 of interlocking relay XRI. Similarly the relay CIIFSC' has a contact 3 3 which when picked up establishes circuits to supply energy to these windings of the relays XRI and XRZ.

When the track section is vacant the track relay CI ITR is supplied with coded energy so that relay CI IFSB establishes the circuits of the windings 3i and 32 of the interlocking relays XRZ and XRI, while relay DIIFSA establishes the circuit of the winding 24 of relay XRZ. As both windings of the relay XRZ are energized, this relay operates in the usual manner to maintain the crossing signal X82 inactive.

The energy supplied by the track transformer BI ITT to the rails of section B! IT feeds to the track relay BI ITR and produces code following operation of the contacts of the relay. During the picked-up periods of the relay contacts, contact 36 establishes the circuit of the primary winding of the track transformer AI ITT so that impulses of energy of the same code frequency are supplied to the rails of section AI IT as are supplied to the relay BI lTR.

In addition, during the picked-up periods of the contacts of the track relay BI ITR, contact 3? establishes the circuit of the winding of relay BI IFSA. This circuit is interrupted during the released periods of the track relay contacts, but the contact of relay BI IFSA is slow enough in releasing to remain picked up during the intervals between the supply of impulses of energy to the relay winding.

Th relay BI IFSA has a contact 38 which when picked up establishes a circuit to energize the winding 48 of relay XRI. Accordingly when the track stretch is vacant the windings 40 and 32 of interlocking relay XRI are both energized and this relay operates in the usual manner to maintain the crossing signal XSI inactive.

The coded energy supplied to the rails of section AI IT feeds to the track relay AIITR and produces code following operation of the contacts of the relay, while the decoding equipment, not shown, associated with the relay AI ITR conditions the signal IIS to display its clear indication and energy of the code frequency is supplied to the rails of section IIlT.

Operation of equipment on passage of a train in normal direction of traffic When a train moving in the normal direction of traffic, that is, from left to right, enters section AIIT, the track relay AIITR, is shunted and its contacts cease to follow code with the result that the decoding equipment, not shown, associated with th relay conditions the signal I IS to display its stop indication, while the energy supplied to the rails of section IIJT is changed from 180 code frequency to a difierent frequency, such as 75 code frequency.

When the train advances far enough to enter section BE IT the track relay BI ITR is shunted and its contact 36 interrupts the supply of energy to the transformer AI ITT, while contact 31 interrupts the circuit of the winding of relay BI I FSA. Accordingly contact 38 of relay BI IFSA becomes released and interrupts the circuit of the winding 40 of interlocking relay XRI so that the armature controlled by this winding becomes released and initiates operation of the crossing signal XSI to warn users of the highway of the approach of a train.

When the train advances far enough to enter section CI IT the contacts of the track relay CI ITR become released and contact interrupts the supply of energy to the track transformer BI ITT, while contact 2'! no longer periodically engages its front contact to supply energy to the winding of relay Cl IFSB. Accordingly, the contacts of relay CI IFSB become released and contact interrupts the circuits of the winding 32 of relay XRI and of winding 3| of relay XRZ, While contact 29 establishes a circuit to supply steady uncoded energy to the track transformer BI ITT.

On interruption of the supply of energy to the winding 32 of relay ml the armature controlled by this winding is prevented from moving to its released position because the other armature of the relay has previously become released.

On interruption of the circuit of the winding 3! of interlocking relay XRZ, the armature controlled by this winding becomes released and initiates operation of the crossing signal XSZ to warn users of the highway of the approach of a train.

On the supply of steady energy to the track transformer BIITT over the circuit established on release of contact 29 of relay Cl IFSB, steady energy is supplied to the rails of section BIIT, but as long as any portion of the train remains in section Bl IT the track relay BI ITR continues to be shunted. However, when the rear of the train vacates section BIIT the steady energy supplied to the rails of the section feeds to the track relay Bl ITR and causes its contacts to pick up and remain picked up.

When contact 36 of track relay BI ITR is picked up steady energy is supplied to the transformer AI ITT, and by it to the rails of section AIIT so that the contacts of the track relay AI [TR become picked up. The signal HS, however, continues to display its stop indication as long as steady energy is supplied to the track relay AI ITR.

On picking up of contact 31 of the track relay Bi ITR the circuit for supplying energy to the winding of the relay BI IFSA is established and contact 38 of this relay becomes picked up to establish the circuit of the winding 40 of relay XRI. The armature which is controlled by this winding thereupon becomes picked up to discontinue operation of the crossing signal XSI. This is proper since the train will have passed beyond the intersection which is protected by the crossing signal XSI.

On picking up of the armature controlled by the winding 40, because of the internal construction of the interlocking relay, the armature controlled by the winding 32 is prevented from moving to its released position even though the winding 32 is deenergized. Accordingly on picking up of the armature controlled by the winding 40 operation of the crossing signal XSI is discontinued.

As the train proceeds through the track stretch and enters section DI IT the track relay DI iTR is shunted and its contacts become released. On release of contact 20 of the track relay DI I'IR a circuit is established to supply steady uncoded energy to the transformer CI I TT so that steady energy is supplied to the rails of section CI IT, but as long as any portion of the train remains in section Cl IT the track relay CI ITR continues to be shunted.

On release of contact 2| of the relay DI ITR. the circuit for supplying energy to the winding of the relay DI IFSA is interrupted and its contact 23 becomes released to interrupt the circuit of the winding 24 of relay XR2. On deenergization of the winding 24 the armature controlled by this winding moves towards its released position, but, because of the internal construction of the interlocking relay, this armature is prevented from moving all of the way to its released position.

When the train advances far enough to vacate section CI IT the steady energy supplied to the rails of section CIIT feeds to the track relay CHTR and causes the contacts of this relay to become picked up and to thereafter remain picked up.

On picking up of contact 25 of the relay CI ITR a circuit is established to supply steady energy to the transformer BI ITT. However, at this time steady energy is already being supplied to the transformer BIITT over the circuit established by contact '29 of relay CI IFSB.

On picking up of contact 21 of relay CIITR the circuit of the winding of relay CIIBSA is interrupted and after a short time interval the contact 28 of this relay becomes released. In the time interval between picking up of contact 2'! of the track relay Cl ITR and release of contact 28 of relay CI IBSA a circuit is established to supply energy to the winding of relay CI IFSB and the contacts of this relay become picked up.

On picking up of the contacts of relay CI IFSB contact 29 interrupts the circuit which it controls for supplying energy to the transformer BI ITI, but at this time energy is supplied to the transformer over the circuit established by contact 25 of the track relay CI ITR so that the supply of energy to the transformer is not interrupted.

In addition on picking up of the contacts of relay Ci IF'SB contact 3!! establishes a circuit to supply energy to the winding 3| of interlocking relay XRZ and to winding 32 of interlocking relay XRI. As a result the armature controlled by winding 32 of relay XRI becomes picked up and this relay is restored to its normal condition, while the armature controlled by winding 3| ofrelay XRZ becomes picked up and discontinues operation of the crossing signal XSZ.

On release of contact 23 of relay CI I BSA while contact 2? of track relay CI ITR is picked up the circuit for supplying energy to the winding of the relay CIIFSB is interrupted, while the circuit for supplying energy to the winding of the relay CI IFSC is established and contact 34 of this relay becomes picked up and establishes circuits for supplying energy to the winding 32 of interlocking relay XRI, and to the winding 3! of interlocking relay XR2.

Because of the slow releasing characteristic of the contacts of relay CI IFSB the contacts of this relay remain picked up for a time interval subsequent to interruption of the supply of energy to the relay winding by release of contact 28 of relay Cl IBSA. The relays Cl lFSB and Cl IFSC are selected so that on release of contact 28 of relay Cl [BSA with resultant interruption of the supply of energy to the winding of relay Cl lFSB and establishment of the circuit to supply energy to the winding of relay Cl lFSC, the contacts of relay Cl lFSB will remain picked up until after the contacts of relay Cl iFSC become picked up. Accordingly at this time the supply of energy to the windings 3| and 32 of the interlocking relays XRZ and XRI is maintained and there is no possibility that the armatures controlled by these windings will become momentarily released after they have once become picked up.

When the train advances far enough in the track stretch to enter the section l2T the track relay lZTR is shunted and the decoding equipment, not shown, associated therewith operates to condition the signal ms to display its stop indication and to change the energy supplied to the track transformer Di lTT from 180 to '75 code frequency. As long as any portion of the train remains in section Di lT the track relay DI ITR continues to be shunted, but when the rear of the train vacates section Di IT energy of the '75 code frequency supplied to the track rails of this section by the transformer DI lTT feeds to the track relay DI lTR and produces code following operation of the relay contacts.

During the picked-up periods of the contact 2! energy is supplied to the winding of relay D! iFSA and contact 23 of this relay becomes picked up and energy is supplied to the winding 24 of interlocking relay XRi so that the armature controlled by this winding becomes picked up and the interlocking relay is restored to its normal condition.

As a result of code following operation of the track relay D! ETR coded or periodically interrupted energy of the 75 code frequency is supplied to the transformer CHTT, and by it to the rails of section Ci lT from which it feeds to the track relay Cl iTR.

On movement of contact 2? of relay Cl [TR to its released position energy is supplied to the winding of the relay Cl IBSA and contact 28 of this relay becomes picked up to establish the circuit of the winding of relay Cl lFSB so that on subsequent movements of the track relay contact 2'! to its picked-up position energy is supplied to the winding of the relay Ci IFSB with the result that contacts 29 and 30 of this relay become picked up.

On picking up of contact 228 of relay C! iBSA the circuit of the Winding of relay Cl IFSC is interrupted, and after a short time interval contact 34 of this relay becomes released. The contact 34 is slow enough in releasing to remain picked up and maintain the circuits of the windings 3i and 32 of the interlocking relays XR2 and KR! until after contact 30 of relay Cl IFSB becomes picked up to establish a circuit to energize these relay windings. Accordingly, the windings of the interlocking relays are maintained energized during the period in which code following operation of the track relay Cl ITR, is initiated and the interlocking relays, therefore, maintain the crossing signals KS! and X82 inactive.

On picking up of contact 29 of relay CZZFSB the circuit controlled thereby for supplying steady uncoded energy to the track transformer BIITT is interrupted, and as a result of code following operation of track relay contact 25 coded or periodically interrupted energy of the same frequency, in this instance the '75 code frequency, is supplied to the track transformer Bl ITT as is supplied to the relay Cl I'IR.

On the supply of coded energy to the transformer Bl ITT, coded energy is supplied to the rails of section Bl lT, and therefrom to the track relay Bl iTR. On the resultant code following 5 operation of the contacts of the track relay BHTR contact 36 interrupts the circuit of the track transformer Al I'IT so that coded or periodically interrupted energy is supplied to the rails of section AHT. At this time contact 31 of relay Bl lTR intermittently interrupts the circuit of the winding of the relay Bl IFSA, but the contact of this relay remains picked up during the intervals between the supply of impulses of energy to the relay winding.

On the supply of coded energy of the 75 code frequency to the track relay Al [TR the decoding equipment, not shown, associated with this relay operates to condition the signal I is to display its caution indication, while the energy supplied to the transformer IUTT is changed from the 75 to the code frequency.

When the train advances far enough in the track stretch to clear section l2T the equipment associated with the section in advance of section lZT operates to supply energy of the 75 code frequency to section i2T, while the decoding equipment, not shown, associated with track relay 12TH operates to condition the signal I2S to display its caution indication and to change the energy supplied to the track transformer Di I TT from 75 to 180 code frequency.

On this change in the code supplied to relay Di iTR this relay operates to repeat the higher code frequency to section Cl lT, While the track relays for sections Cl IT and BI lT similarly repeat the supply of energy of the higher code frequency to the sections in the rear so that energy of the 180 code frequency is supplied to the re lay Al l'IR.

On the supply of energy of the 180 code frequency to the relay Al lTR the decoding equipment, not shown, associated with the relay opcrates to condition the signal Us to display its clear indication.

At this time as the track relays Bi lTR, Cl I TR and DI lTR are responding to coded energy, the equipment associated with these relays maintains the circuits of the windings of the interlocking relays to thereby condition these relays to maintain the crossing signals inactive.

The operation of the equipment on passage of a train in the normal direction of traffic having been explained, its operation in response to movement of a train in the reverse direction of traffic will now be considered.

Opemtion of equipment on movement of a from in the reverse direction of trafiic When a train moving in the reverse direction,

that is, from right to left, enters section l2'1 the relay IZTR is shunted and the signal I2S is conditioned to display its stop indication, while the energy supplied to the transformer DIITT is changed from 180 to 75 code frequency. As a result there is a change in the rate of operation of the contacts of the track relay DII'IR, and of the track relays for the other subsections so that relay Al lTR. is supplied with energy of the '75 code frequency and the signal Us is conditioned to display its caution aspect.

At this time, as the track relays for, the various subsections are responding to coded energy, the circuits of the windings of the interlocking relays are maintained and the interlocking relays operate to maintain the crossing signals inactive.

When the train enters section Di IT the track relay DIITR. is shunted and its contact 2!! establishes the circuit to supply steady uncoded energy to the transformer CI ITT, while contact 2| interrupts the circuit of the winding of relay DI IFSA so that contact 23 becomes released and interrupts the supply of energy to the winding 24 of the interlocking relay XR2. The armature controlled by this winding thereupon becomes released and initiates operation of the crossing signal XSZ to warn users of the highway of the approach of a train.

On the supply of steady energy to the track transformer CIITT subsequent to shunting of the track relay DI ITR, steady energy feeds to the track relay CI ITR and maintains the confacts of this relay constantly picked up with the result that contact 25 establishes a circuit to supply steady uncoded energy to the transformer BI ITT. Accordingly the contacts of track relay BI I'IR are held in their picked-up position and contact 36 repeats the supply of steady energy to section AIIT. The track relay AIITR, therefore, no longer responds to coded energy and the signal IIS is conditioned to display its stop indication, while energy of the '75 code frequency is supplied to section IBT to condition the signal for that section to display its caution indication.

On the supply of steady energy to the track relay CIITR contact 2'! of the relay remains picked up and does not engage its back contact to supply energy to the winding of the relay CI IBSA with the result that after a brief time interval the contact 28 of relay CI I BSA becomes released. Release of contact 28 interrupts the circuit of the winding of relay CI IFSB and establishes the circuit for supplying energy to the winding of relay CIIFSC so that the contacts of relay CI IFSB become released and the contact of relay CI EFSC becomes picked up. The contacts of the relay CI IFSB are slow enough in re-, leasing to remain picked up until after the contact of relay CIIFSC becomes picked up. Accordingly contact 30 of relay CI IFSB maintains the circuits of the windings SI and 32 of interlocking relays XR2 and KR! until contact 34 of relay CI IFSC becomes picked up to establish circuits for supplying energy to these windings. The armature controlled by winding 32 of relay XRI, therefore, remains picked up and maintains the crossing signal XSI inactive at this time.

Similarly as a result of the supply of steady energy to the track relay Bl ITR, contact 31 is held picked up and maintains the circuit of the, winding of relay BIIFSA, while contact 38 of relay CI IFSA is held picked up to maintain the circuit of the winding M! of interlocking relay XRi so that the armature controlled by this winding is held picked up to maintain the crossing signal XS! inactive.

It will be seen, therefore, that when a train moving in the reverse direction of traiiic enters section DIIT, the crossing signal XSZ is placed in operation, while steady energy is supplied to the rails of the subsections CI IT, BI ET and AI IT to maintain the crossing signal XSI inactive and to condition the signal I IS to display its stop r indication.

When the train advances far enough to enter the section CI IT the track relay CI ITR is shunted and its contacts become released. Release of contact 25 interrupts the circuit which it controls for supplying steady energy to the track transformer BI I TT, but at this time contact 29 of relay CI IFSB is released, and accordingly the supply of steady energy to the track transformer BIITT is maintained after release of the contacts of the track relay CI ITR.

On release of the contact 21 of relay CI ITR the circuit for supplying energy to the winding of the relay CIIFSC' is interrupted, and after a time interval contact 3d of relay CI IFSC becomes released to interrupt the circuits of the windings 3I and 32 of interlocking relays X82 and XRI.

As a result of deenergization of winding 32 of interlocking relay XRI the crossing signal XSI starts to operate, while on deenergization of winding 3| of interlocking relay XRZ the armature controlled by this winding moves towards its released position, but is prevented from moving all of the way to this position because the armature controlled by the winding 24 of the relay is already in its released position.

As the train continues and the rear of the train vacates section IZT, the coded energy supplied to the rails of this section feeds to the track relay IZTR, and produces code following operation of the relay with the result that signal IZ'S is conditioned to display a proceed aspect, while energy of the 180 code frequency is supplied to the rails of section DI IT. When the rear of the train vacates section DHT the track relay DI ITR responds to coded energy and supplies energy of 180 code frequency to the rails of section CI IT, while energy is supplied to the winding of relay DI IFSA so that contact 23 becomes picked up to supply energy to the winding 24 of the interlocking relay XRZ. The armature controlled bywinding 24 thereupon become picked up to discontinue operation of the crossing signal XSI.

When the train advances into section BI IT the track relay BI ITR is shunted and its contact 36 remains in its released position so that energy is not supplied to the rails of section AI IT and the contacts of the track relay AI I'IR become released, while the signal IZS continues to display its stop indication.

On release of contact 31 of relay Bl ITR the circuit of the winding of relay BI IFSA is interrupted and contact 38 of the relay becomes released to interrupt the supply of energy to the winding 40 of interlocking relay XRI The armature controlled by this winding thereupon moves towards its released position, but is prevented from moving all of the way to that position because the armature controlled by winding 32 is already in its released position.

When the rear of the train Vacates section CI IT, coded energy feeds to the track relay CI ITR.

and produces code following operation of the contacts thereof, and on movement of the contact 21 of the track relay to its picked-up position energy is supplied to the winding of relay CI IFSB over the circuit which includes front contact 28 of relay CI IBSA. Contact 28 of relay CI IBSA is picked up at thi time since energy is supplied to the winding of this relay when the track relay contacts are released, while on continued code following operation of the track relay contacts the windings cf the relays Cl IBSA and CI IFSB On picking up of contact 29 of relay CI IFSB the circuit controlled thereby for supplying steady energy to the track transformer BI ITT is interrupted, and thereafter coded energy is supplied to the track transformer over the circuit controlled by contact 25 of track relay CI ITR.

On picking up of contact 30 of relay CI IFSB energy is supplied to the winding 32 of interlocking relay XRI to pick up the armature controlled by this winding, and thereby cut off operation of the crossing signal XSI. Energy is also supplied to the winding 3I of relay XR2 and the armature controlled by this winding becomes picked up to restore the relay XRZ to its normal condition.

As the train continues and enters the section AI IT the track relay AI ITR is shunted and its contacts remain released even after the rear of the train vacates section BI IT so that coded energy is supplied to the rails of section AI IT. Accordingly the signal I IS continues to display its stop indication.

When the rear of the train vacates section BI IT the track relay BI ITR responds to coded energy and contact 36 establishes the circuit to supply impulses of energy to the track transformer AI ITT, while contact 3'! establishes the circuit to supply impulses of energy to the winding of relay BI IFSA. On picking up of the contact 38 of relay CI IFSA energy is supplied to the winding 40 of relay XRI and the armature controlled by this winding becomes picked up to restore the relay to it normal condition.

When the train advances far enough to vacate section AI IT coded energy feeds to the track relay AI ITR and the signal H8 is conditioned to display its clear indication.

It will be seen, therefore, that the system provided by this invention is arranged to insure proper operation of both the highway crossing signals and the railway traffic controlling signals on movement of a train through the track stretch in either direction. 7

This system is also arranged so that if the equipment does not function in the intended manner a dangerous condition will not be created.

The code following track relays BI I TR and CI ITR are arranged so that their contacts when picked up establish circuits to supply energy to the rails of the adjacent section in the rear, while a contact of each of these relays is operative when picked up to establish a circuit to supply energy to a relay which supplies energy to a winding of an interlocking relay.

If a code following track relay is equipped with metal to metal contacts there is a possibility that these contacts may fuse together and remain in their picked-up position when the relay winding is not energized. If this occurs a crossing signal will not operate on the approach of a train.

If, for example, the contacts of the relay BI ITR fuse together and remain picked up steady energy.

will be supplied to the rails of section AI IT, while energy will also be supplied to the winding of relay BI IFSA. The supply of energy to the relay BIIFSA will be continued even if a train moving in the normal direction of trafiic enters section BI IT and shunts the track relay BI I TR since it is assumed that the relay contacts are fused together and do not become disengaged on shunting of the track relay. Accordingly contact 31 will maintain the circuit to supply energy to the winding of relay BI IFSA, while contact 38 of relay BI IFSA maintains the supply of energy to the winding 40 f interlocking relay XRI. The relay XRI, therefore, maintains the crossing signal XSI inactive.

However, when the contacts of the relay BI ITR are held in their picked-up position, steady energy is supplied to the track relay AI ITR and the equipment associated with this relay conditions the signal I IS to display its stop indication, while the energy supplied to the rails of section IDT is such as to condition the signal for that section to display a restrictive proceed indication. Accordingly, if under these conditions a train passes through the track stretch it will be compelled to stop or greatly reduce its speed before passing signal HS, and, therefore, will be traveling at a slow speed when it enters section BI IT and approaches the intersection when the crossing signal is not operating. As the train is traveling at a slow speed it does not present a great hazard to users of the highway even though the crossing signal is not operating, while the engineer of the train has ample time to blow the locomotive whistle and warn users of the highway.

Similarly, if the contacts of relay CI I TR fuse together steady energy will be supplied to the rails of section B! IT, while energy will be supplied to the winding of relay CI IFSC so that its contact 34 is picked up and establishes the circuit to supply energy to the winding 3| of interlocking relay XRZ.

As a result of the supply of steady energy to the rails of section BI IT, the track relay BI ITR supplies steady energy to section AI IT and the signal IIS is conditioned to display its stop indication.

On movement of a train through the track stretch, the relay BI ITR is shunted on entrance of the train into section BI IT, and operation of the crossing signal XSI is initiated in the normal manner as explained above. When the train enters section CI IT the contacts of the track relay CI I TR fail to release and relay CI IFSC maintains the circuit of the winding 3| of interlocking relay XRZ so that the crossing signal XSZ does not start to operate when the train enters section CI IT.

However, as pointed out above, the signal II S will have been displaying its stop indication, so the train will be traveling at a slow speed when it approaches the highway intersection and will not present a serious hazard.

From the foregoing it will be seen that the system provided by this invention is arranged so that the maximum degree of safety is obtained in the event the contacts of a track relay fuse together so that they fail to separate when the relay winding is deenergized. The system is arranged so that the signals governing movement of trains in the track stretch are caused to display their most restrictive indication, and the only adverse effect of fusing of the contacts of a track relay is failure of a crossing signal to function in the intended manner. The effect of this failure is minimized because of the slow speed of the trains at the time.

The possibility of failure of the equipment to operate in the intended manner because of fusing together of the contacts of a track relay is extremely remote, but even this possibility can be eliminated by equipping the track relays with infusible contacts. For example, the track relays might be provided with silver to impregnated carbon contacts, instead of silver to silver contacts.

It will be seen that the system provided by this invention is adapted for use in track stretches where there are a plurality of highway intersections within a single track or block section, and that the system makes it possible to employ back contact coding at the cut section nearest the exit end of the section. This is desirable to prevent code distortion in the remainder of the section.

The track relay for the cut section to which energy is supplied by the back contact coding apparatus has associated therewith means to detect code following operation of the track relay and to also detect the steadily energized condition of the track relay.

The relay CI IFSB is controlled in such a manner that it is energized when and only when the track relay is responding to coded energy, while the relay CIIFSC is energized when and only when the track relay CI ITR is steadily energized.

Construction and. operation of modification shown in Fig. 2 of the drawing In Fig. 2 of the drawing there is shown a modified form of apparatus which may be employed with the track relay for section Ci IT. As shown the track relay CIITRA has associated there I with a decoding transformer CI IDT, and auxiliary relays CI IFSD and CI IFSE. The decoding transformer CIIDT has a primary winding 50 and a secondary winding 5I. The track relay CI ITRA has a contact 52 which when picked up establishes connection from terminal B of the local source of direct current to one end terminal of the winding 50 and when released establishes connection to the other end terminal of the winding 55, while the center terminal of the winding 5!! is connected to terminal C of the source of current. The relay Cl ITRA ha a contact 53 which when picked up establishes connection from one end terminal of the transformer secondary winding 5| to a terminal of the winding of the relay CI IFSD, and when released.

establishes connection from the other end terminal of the winding 5| to the relay winding. The center terminal of the winding 5| is connected to the other terminal of the winding of the relay CI IFSD. Accordingly when the track relay CI ITRA is responding to coded energy, the end ortions of the transformer primary winding 50 are alternately energized so that current is induced in the secondary winding 5|, while contact 53 rectifies the current supplied from the secondary winding to the winding of relay CI IFSD.

The relay CIITRA has a contact which when picked up establishes a circuit to supply energy to the track transformer BI I'IT so that when the relay is supplied with coded energy, energy of the same code frequency is supplied to the adjacent section in the rear, and when the track relay contacts are constantly picked up steady energy is supplied to the adjacent section in the rear.

The track relay CIITRA has a contact 55 which when picked up establishes a circuit to supply energy to the winding of relay CI IFSE. while contact 56 of relay CIIFSD when picked up also establishes a circuit to supply energy to the winding of relay C I IFSE.

The relay CI IFSD has a contact 58 which when released establishes a circuit to supply steady energy to the track transformer BI ITT, while relay CI IFSE has a contact 69 which when picked up establishes circuits to supply energy to the windings 3| and 32 of the interlocking relays XRZ and XRI.

In operation, when the track stretch is vacant so that coded energy is supplied to the track relay C'I ITRA, energy is supplied through the decoding transformer CI I DT to the winding of the relay GIIFSD, and contact 56 of this relay is picked up to establish a circuit to supply energy to the winding of relay CI IFSE so that contact I of relay CI IFSE is picked up and establishes the circuits of the windings of the relays XRI and XRZ so that these relays maintain the crossing signals inactive. In addition, contact 58 of relay CIIFSD is picked up and interrupts the circuit which it controls for supplying energy to the track transformer B! I TT so that the track transformer is supplied with coded energy over the circuit controlled by track relay contact 25.

When a train traveling in the normal direction of traffic enters section CIIT, the track relay CI ITR is shunted and the contacts of the relay remain in their released positions so that energy is no longer supplied through the transformer CI IDT to the winding of relay CI IFSD. Accordingly the contacts of relay OI iFSD become released and contact 58 establishes the circuit to supply steady energy to the track transformer BI ITT, and steady energy is supplied therefrom to the track relay for section BI IT to discontinue operation of the crossing signal controlled by interlocking relay XRI when the train vacates section BI IT.

On release of contact of relay CI iFSD the circuit of the winding of relay CI IFSE is interrupted, and the contact of relay CI IFSE becomes released to interrupt the circuits for supplying energy to the windings 3i and 32 of interlocking relays XR2 and XRI. Accordingly relay XR2 initiates operation of the crossing signal controlled thereby.

When the train advances far enough to vacate section CI IT steady energy supplied to the rails of this section by the equipment associated with the adjacent section in advance feeds to the track relay CI ITRA and picks up the contacts thereof. On picking up of contact 55 of relay CIITRA energy is supplied to the winding of relay C'I IFSE and contact 60 of this relay becomes picked up to establish the circuits for supplying energy to the windings of the interlocking relays XRI and XRZ. The relay XRZ, therefore, operates to discontinue operation of the crossing signal controlled thereby.

When the train advances far enough in the track stretch to vacate the section in advance of section CI IT coded energy is supplied to that section, while the supply of steady energy to the rails of section CI IT is out OE and coded energy is supplied to the rails of section CI IT and track relay CI ITRA responds to coded energy.

On movement of contact 55 of the track relay CIITRA to the released position'the circuit of the winding of relay C'I IFSE is interrupted, but the circuit is reestablished on picking up of the track relay contacts, and also on picking up of the contacts of relay Ci IFSD. When code following operation of the track relay contacts is initiated energy is supplied through the transformer CI IDT to the relay C'I IFSD and the contacts of this relay become picked up so that con tact 56 establishes a circuit to supply energy to the winding of relay CI IFSE, while contact 58 interrupts the circuit which it controls for supplying steady energy to the track transformer BI ITT. The supply of energy to the track transformer is thereafter controlled by contact 25 of the track relay Cl lTRA so that coded energy is supplied to the transformer.

The contact 60 of the relay CHFSE is slow enough in releasing to remain picked up until the circuit for supplying energy to the relay winding is reestablished by picking up of the track relay contact 55 or of contact 55 of relay Ci IFSD. Accordingly on a change in the supply of energy to the track relay from steady to coded energy contact E0 of relay Ci EFSC remains picked up and maintains the circuits of the windings of the interlocking relays XRI and XR2 so that these relays maintain the associated crossing signals inactive.

When a train traveling in the reverse direction of traffic enters the section in advance of section Cl IT, the equipment associated with that section operates as described in detail above to supply steady energy instead of ceded energy to the rails of section Cl lT. On this change in the energy supplied to track relay Cl ITRA, the contacts of this relay remain picked up and energy is no longer supplied through the transformer Cl MDT to the relay Cl IFSD. Accordingly the contacts of this relay become released and contact 58 interrupts the circuit which it controls for supplying energy to the winding of relay CI iFSE. However, since track relay contact 55 is picked up energy continues to be supplied to the winding of relay Cl lFSE so that its contact 53 is maintained picked up to maintain the supply of energy to the winding 32 of interlocking relay XRi to thereby cause that relay to maintain the associated crossing signal inactive.

When contact 58 of relay Cl lFSD becomes released it establishes a circuit to supply steady energy to the track transformer BUTT, while steady energy is also supplied to this transformer over the circuit controlled by track relay contact 25.

When the train advances far enough to enter section Ci IT the track relay C! ITRA is shunted and its contacts become released. On release of contact 25, the circuit which it controls is interrupted, but steady energy continues to be supplied to the track transformer BI ITT over the circuit controlled by contact 58 of relay Ci IFSD.

On release of contact 55 of the track relay C! ETRA the circuit of the winding of relay CHFSE is interrupted and the contact 60 becomes released to interrupt the supply of energy to the winding 32 of interlocking relay XRI so that this relay initiates operation of the associated crossing signal.

When the train advances far enough to clear section Cl lT, coded energy is again supplied to the track relay Cl I TRA and energy is again supplied to the windings of relays Cl IFSD and Cl lFSE so that contact 60 reestablishes the circuit for supplying energy to the windings of relays XZRI and XRZ, and relay XRI operates to discontinue operation of the associated crossing signal. On picking up of contact 58 of relay C! IFSD the supply of steady energy to the section in the rear is cut off and thereafter coded energy is supplied to section Bl l'I over the circuit controlled by track relay contact 25.

It will be seen, therefore, that the modification shown in Fig. 2 of the drawing incorporates means to detect both code following operation of the track relay contacts and to detect the steadily energized condition of the track relay. The decoding transformer Cl iDT and the relay Cl lFSD provide means to detect code following operation of the track relay, and if for any rea- 75 son the track relay contacts remain in either their released or picked-up positions the contacts of relay CI IFSD become released and steady energy is supplied to the section in the rear with the result that the signal at the entrance to the section is conditioned to display its most restrictive indication.

When the track relay contacts are steadily picked up the relay C'l IFSE is energized and its contact 68 is picked up to establish the circuits to supply energy to the interlocking relays and condition these relays to prevent operation of the crossing signals. This makes it possible to employ steady energy to discontinue operation of crossing signals when a train clears a subsection, or to prevent their operation prior to entrance of a train into a section.

It will be seen that the modification shown in Fig. 2 may be incorporated in the system shown in Fig. 1 and provides means to distinguish between code following operation of the track relay, the steadily energized or the deenergized condition of the relay. In the system shown in Fig. 2 the relay Cl lFSD detects code following operation of the track relay and controls the circuit for supplying steady uncoded energy to the rails of the section in the rear, while the relay Cl lFSE detects the deenergized condition of the track relay and controls the circuits for supplying energy to the windings of the interlocking relays.

Although I have herein shown and described only one form of railway trafiic controlling apparatus together with one modification thereof embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railroad track having a pair of track rails having insulated joints therein to divide the track stretch into a plurality of successive track sections including a forward, an intermediate and a rearward track section, said track stretch including a first highway intersection located adjacent the rear of the forward section and a second highway intersection located adjacent the rear of the intermediate section, a first crossing signal protecting the first intersection and a second crossing signal protecting the second intersection, a first control relay operative when and only when energized to maintain the first crossing signal inactive, a second control relay operative when and only when energized to maintain the second crossing signal inactive, each of said track sections having a code following track relay having a winding receiving energy from the rails of said section, means governed by traffic conditions in advance of the forward section for supplying coded energy to the rails of said forward section, the track relays for the forward and intermediate sections each having associated therewith means operative when said relay is responding to coded energy to supply to the rails of the adjacent section in the rear energy of the same code frequency as is supplied to said track relay, means operative when the forward section track relay is not energized to supply uncoded energy to the rails of the intermediate section, means operative when and only when the intermediate section track relay is responding to coded or uncoded energy to supply energy to the first control relay. a supply circuit for supplying iincodedenergy to the rails of the rearward section, means responsive to code following operationof the intermediate section track relay for interrupting said supply circuit, and means operative when and only when the rearward section track relay is responding to coded or uncodedenergy to supply energy to the second control relay.

2. In combination, a stretch of railroad track having a pair of track rails having insulated joints therein to divide the track stretch into a plurality of successive track sections including a forward, an intermediate and a rearward track section, said track stretch including a first highway intersection located adjacent the rear of the forward section and a second highway intersectionlocated-adjac'ent therear of the intermediate section, a firstcrossing signal protecting the first intersection and a second crossing signal protecting the second intersection, a first 'control relay operative. when and'only when energized to maintain the first crossing signal inactive, a second control relay operativewhen and only when energized to maintainthe second crossing signal inactive, each of said track sections having a code following track relay havingawinding receiving energy from the rails of saidseotion, means governed by traflic conditions in advance of the forward section for supplying coded energy to the rails of said for-ward section, a supply circuit through which energy is supplied to the rails of the intermediate section, the forward section track relay being operative when energized to interrupt said supply circuit, wherebyv on the supply of coded energy to s aid forward section trackrelay energy of the same code frequency is supplied to the rails of the intermediate section and when energy is not supplied to said forward section track relay uncoded energy is supplied to the rails of the intermediate section, means operative when and only when the intermediate section track relay is supplied withcoded oruncoded energy to supply energy to the firstcontrol relay, a circuit for supplying uncoded energy to the rails of the rearward section, fmeans operative;

when the intermediate section track relay'is'sup plied with coded energy to interrupt said lastnamed circuit and to supplyito the rails of the rearward section'coded energy of' the same code frequency as is supplied tosaid intermediate section track relay, andmeans operative when and only. when therearwardsection track relay is supplied with coded or ,unco'ded energy for supplying energy to the second control relay,

3. In combination, a stretch of railroad tracks having a pair of track rails having insulated joints therein to divide the track stretch into a plurality of successive track sections including a forward, an intermediate and a rearward section,

said track stretch including-afirst highway intersection, located adjacent. the rear of the intermediate section and a second highway intersection located adjacent the rear of the forwardsection, a first crossing signal protecting the first intersection and a second crossingsignal protecting the second intersection, a first control relay controlling the first crossingsignal, asecond control relay controlling the second crossing signal, each of said control relays being operative when and only when energized to maintain the associated crossing signal inactive, eachof said track sections having a code following track relay having awinding receiving energy from the rails of the said section, means governed by trafflc conditions in advance of the forward section for supplying coded energy tothe rails of said forward section, the track relays for the forward and in'- termediate sections each having associated therewith means responsive to code following operation of such relay to supply to the rails of the adgacent section in the rear energy of the same code frequency as is supplied to such track relay whereby when the track stretch is vacant energy of the same code frequency is supplied to the rails of the rearward section as is supplied to the .rails of the forward section, the forward section track relay having associated therewith means operative when said relay is not energized to supply uncoded energy to the rails of the intermediate section, a supply circuit for supplying uncoded energy to the rails of the rearward section, means responsive to code following operation of the intermediatesection track relay for interrupting said supply circuit, whereby when either the forward or intermediate section is occupied uncoded energy is supplied to the rails ofthe sections in the rear, means responsive to the supply of coded or uncoded energy to the track relay of the rearward section for supplying energy to the second control relay, and means responsive to the supply of coded or uncoded energy to the track relay of the intermediate section for supplying energy to the first control relay. l in combination, a stretch of railroad track having a pair of track rails having insulated oints therein to divide the track stretch into a plurality of successive track sections including a forward, an intermediate and a rearward section,

.said track stretch including a first highway intersection located adjacent the rear of the forward section and a second highway intersection located adjacent the rear of the intermediate section, a first crossing signal protecting the first intersection, a second crossing signal protecting the second intersection, a first interlocking relay controlling the first crossing signal and a second interlocking relay controlling the'second crossing s1gnal,each of said interlocking relays having a pair of windings and being operative on deenergization of either of said windings to initiate operation of the associated crossing signal, means governed by trafiic conditions in advance of said forward section for selectively supplying to the rails of the forward section energy coded at one of a plurality of different frequencies, each of said track sections having a code following track relayhaving a winding receiving energy from the rails of the said section, means associated with the rearward section track relay and operative when said relay is supplied with coded or uncoded energy to supply energy to one winding of the second interlocking relay, means associated with winding of the first interlocking relay, the track relays of the forward and intermediate sections each having associated therewith means operative when said relay is supplied with coded energy to supply energy of the same code frequency to the rails of the adjacent section in the rear,

the track relay of the forward section being operative when deenergized to establish a circuit to supply uncoded energy to the rails of the intermediate section, the track relay of the intermediate section being operative when deenergized or when supplied with uncoded energy to establish a circuit to supply uncoded energy to the rails of the rearward section.

. 5. In combination, a stretch of railroad track having a pair of track rails divided by insulated joints into successive track sections, the rails of one of said sections being divided by insulated jointslinto a plurality of subsections including a forward, an intermediate and a rearward subsection, said track section including a first high- Way intersection located adjacent the rear of the forward subsection and a second highway intersectionlocated adjacent the rear of the intermediate subsection, a first crossing signal protecting the first intersection, a second crossing signal protecting thesecond intersection, a first control. relay controlling the first crossing signal, a second control relay controlling the second crossing signal,v each of said control relays being operative, when energized to maintain the associated crossing signal inactive, means governed by traffic conditions in advance of said onesection for selectively supplying to the track'rails Of! the forward subsection coded energy periodically interrupted at either of a plurality of different code frequencies, each of said subsections having a code following track relay having a winding receiving energy from the rails of the associated subsection, the track relays of the forward and intermediate subsections each being operative when supplied with coded energy to effect the supply of coded energy of the same code frequency to the rails of the adjacent subsection in the rear, whereby when said section is vacant energy of the same code frequency is supplied to the rearward subsection track relay as is supplied to the rails of the forward subsection, a signal capable of displaying a plurality of difierent indications and governing trafiic in said one track section, the rearward subsection track relay being adapted to have associated therewith means operative when said rearward subsection'track relay is not supplied with energy or is supplied with uncoded energy to condition said signal to display its most restrictive indication, said means being selectively responsive to the supply of coded energy of difierent frequencies to said track relay to condition said signal to display one or another of its less restrictive indications, the track relay of the forward subsection being operative when deenergized to effect the supply of uncoded energy to the rails of the intermediate subsection, the track relay of the intermediate subsection being operative when deenergized or when steadily energized to efiect the supply of uncoded energy to the rails of the rearward subcoded or uncoded energy to supply energy to the second control relay.

6. In a coded railway signaling system, in combination, astretch of railroad track divided by insulated joints into successive track sections, the, rails of one, of said sections being divided by insulated joints into a plurality of subsections including a forward, an intermediate and a rear- .ward subsection, said track section including. a

a reed? highway intersection located adjacent the rear of the intermediate'subsection, a crossing signalprotecting said intersection, a control relay controlling said' crossing signal, said relay being operative when energized to maintain said crossing signal inactive; means governed" by traffic conditions in advance of said track section for supplying coded energy tothe rails of said forward subsection, each of said subsectionshaving a code following track relay having a winding receiving energy from the rails of the associated subsection; the track; relays of the forward and intermediate subsectionseach being operative when supplied with coded energy to effect the supply of COdEdBHGIgY of the same code frequency-to-the' rails of the adjacent subsection in th'erear', whereby'whenthe track section is vacant energy of the same code frequency is supplied to therearward subsection track relay as is supplied to therailsof the forward subsection, means operative when thet'rack relay of the forward subsection is'not energized to supply uncoded energy to the 'rails'of thein'termedia'te subsection, means operative when-thetrackrelay of the intermediate" subsection isdeenergized' or is steadily energizedtci'effect the supply of uncoded energy to the rails of the rearward subsection', and means operativewhen' the track r'elayof the rearward subsectionis supplied with-either coded or uncoded energy to supply energy'tosaid control relay.

7. In a' coded rail-way signaling system, in combination; a stretch of railroad track divided by insulated-joints intosuccessive track sections, the rails of'one'of'said sections being divided by insulated joints into a; plurality of subsections including aforward, an intermediate and. a rearward subsection, saidtrack section including a highway intersection located adjacent the rear of theintermediate subsection; a crossing signal pro tecting said intersection, a control relay controllingsaid crossing signal; saidrelay being operative when energized to maintain said crossing signal inactive; ineansgoverned by traffic conditions in advance of said traclssectionfor supplying coded energy to the rails'of said forward subsection, each of said subsections having a code following trackrelay having a winding receiving energyfrom th'e rails ofthe associated subsection, the" track relays ofthe forward and intermediate subsections each beingoperative when supplied with coded energy to effect the supply of coded energy of the same code frequency to the rails of the adjacent'subsection inthe rear, whereby when thetr'acksectionis vacant energy of the same code frequency is supplied-to the rearward subsection"track-relayas"is supplied to the rails of the forwardsubsection; means operative when the track relay of the forward subsection is not energized to supply uncoded energy to the rails of the intermediate subsection, an auxiliary relay associated with the track relay for the intermediate subsection; said auxiliary relay being operative when deenera'ized to establish a circuit to supply uncodede'n'ergy to the" rails of said rearward subsection; means responsive to code followingopera'tion "of said intermediate subsection-track relay'fo'r supplying energy to said auxiliar'y relay, and means operative on the supply of either coded. 'or' uncoded-energy to the rearward subsectiont'rack: relay for supplying energy to said control relay.

HOWARD A; THOMPSON.

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